Protect E-Mail Addresses

Written by Martin Geber on September 29, 2004 at 8:14 p.m. Filed unter: PHP. No Comments yet. Trackback URL.

Everybody knowes these nasty little emails trying to sell you Viagra and stupid stuff like this. Everybody hates those emails, which were send by a mass-sender which got your email address from the WWW.
These spam senders are crawler like Google or Yahoo! but they are just looking for data which matches this sheme: anything@domain.top-level-domain.
So there are pages like PHP.net which totally don't link any correct email addresses at all, they makes it necassery to edit the address in your email program. At the page of PHP Classes is this sheme used: anything at domain . top-level-domain. Both pages trys to protect the email addresses of their users, what is laudable, and necassery.

But in my opinion this isn't the right way to save email addresses, as it forces you to type manually an address to your email program. But how can we sheet the crawlers of those spam engines in a way which doesn't make it necassery to edit anythink after clicking the link? There are some huge JScripts which use the document.write() function and variables, but this is difficult for PHP generated websites and takes a longer execute time for the HTML on clients side, there must be another way.

And there is one, indeed. The German page php4u.net published a very useful function, which encrypts all email addresses into a charset the spam engine wouldn't understand but which is accepted by the programs: You will see the correct address by hovering the link as well as you see it when you click the link. Here is the pretty short code:

<?php
    /**
     * Encode E-Mail Addresses.
     * 
     * @param    string    $mail: E-Mail Address
     * @return   string    Encoded E-Mail Address
     */
    function no_spam($mail) {
        $str = ""
        $a = unpack("C*", $mail);
        foreach ($a as $b)
        $str .= sprintf("%%%X", $b);
        return $str;
    }
    // Usage
    $mail = no_spam('test@mail.com');
    $link  = '<a href="mailto:' . $mail . '">Email</a>'
    echo $link;
    // A subject is also possible:
    $mail = no_spam('test@mail.com');
    $link  = '<a href="mailto:' . $mail . '?subject=Test%20Subject">Email</a>'
    echo $link;
?>

When your email address would be test@mail.com, the returned string will be: %74%65%73%74%40%6D%61%69%6C%2E%63%6F%6D So your link would be: <a href="mailto:%74%65%73%74%40%6D%61%69%6C%2E%63%6F%6D">Email</a>.

I'm using this function for my page Emma Watson Empire and as long as I didn't gave my email address to anyother page, I didn't get any spam. Just try to use this function, you and your vistors will love it.

Help to tidy up the inboxes of your vistors and your own!

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